1 out of 4 battery cells dead

[Sam3010]

Saw the trackpad of the laptop slightly higher than it should be, thought it might be the batteries underneath expanding so went into the UEFI and checked its state. 
It showed the voltage for cell 4 as 0mV, whilst the other three are at 4331/4332mV

Im aware that I should be changing the battery ASAP but I just can't at the moment, so I was wondering whether I could still use the laptop for atleast another month or two safely?

I keep it plugged in 24/7 and never run it on battery power.

I've been using this laptop for 5 years, did a battery swap three years ago due to it dying completely.

Daily use case being general browsing, heavy gaming and video editing/3d rendering.

[Huffer]

The battery health app shows info for 4 cells. Your battery is a 3-cell battery. When there is no 4th cell it just registers zero. So your fourth cell is not dead; it does not exist. You can use the laptop safely. 

[Sam3010]

Thanks for the help, I forgot to add in a detail which is the UEFI diagnostics issued a warning as it cannot run tests on the battery, is that anything to be concerned about? I ran the diagnostics again today and everything ran smoothly and the battery was deemed fined by the system (no warnings, no failed checks or unable to run checks).

[Huffer]

So you can run the tests now? In order to say all is OK I might want to see the test results but if the test runs all the way through and indicated the battery is OK it very likely is. 

[Sam3010]

I'm not quite sure on how to copy the test results in the UEFI but as i ran the battery test, it again issued the same warning as mentioned above about it not being able to test the battery. 

[Huffer · Accepted solution]

If its swollen I would get it out of there before it does any more damage. A swollen battery can still test fine. Leave it plugged in. You can run it with no battery but if you remove power all the CMOS settings like clock time, etc. will revert to default. The mains battery is also the RTC /BIOS battery.